Adidas Prime X Strung 3 First Run Review: The Illegal Race Shoe Gets Softer

Introduction

The Adidas Prime X Strung 3 is one of the most unusual shoes in the running world right now: a deliberately over-stacked, over-built marathon shoe that ignores World Athletics stack rules entirely. The first Prime X Strung OG became a cult favorite for combining a big foam stack with a surprisingly light, fast ride, and the Prime X Strung 2 traded some of that magic for stability. The question for version three is simple: did Adidas finally get the balance right?

Out of the box, the answer is nuanced. The Strung 3 lands between the OG and the 2, softer in the heel and more forgiving at moderate paces, but it is still a heavy, quirky shoe that asks a lot from the runner wearing it.

What Makes the Prime X Strung 3 Different

This is a five-layer construction in the forefoot: Lightstrike Pro rods beneath a Lightstrike Pro plate, with a large soft foam puck up front and tall foam elsewhere. Adidas calls this its illegal marathon race shoe for a reason. Measured heel stack came in above 50 mm, with roughly 45 mm at the tallest forefoot point, about 10 mm more than the brand’s regular marathon race shoe. The plate even extends out the back of the heel, a detail that generated plenty of commentary when early images leaked.

The Strung upper is the other headline feature. It is a spiderweb-like woven construction, starchy out of the box, and it is a big part of why this shoe costs $300. It looks fantastic in person, though the practical benefit over a conventional upper is debatable, especially given some heel slip noted during testing.

How the Strung 3 Compares to the OG and the Strung 2

The lineage matters here. The OG Prime X Strung was built around a question: what is the fastest possible marathon shoe if you ignore all the rules? Around 50 mm of heel stack, the best version of Lightstrike Pro, multiple plates, and a race-day feel at a reasonable weight. The Strung 2 responded to consumer feedback by widening the base and firming things up, which made it more stable but heavier and slower, losing the special character of the OG.

The Strung 3 keeps the wider footprint of the 2 but softens the ride considerably. Caliper measurements put the heel width at 82 mm, nearly matching the 2’s 83 mm and far wider than the OG’s 74 mm. The forefoot measures around 125 mm at the widest point, one of the widest tested, 7 mm wider than the Strung 2. So: wider on the forefoot, narrower at the heel than the 2, and much softer throughout.

Specs and Build Quality

Measured weights came in at roughly 308.68 g on the right shoe and about 310 g on the left. That is about 15 g lighter than the Strung 2’s 325 g, but still around 35 g heavier than the OG’s 275 g, roughly a 10 percent penalty. For context, that weight puts it closer to a fun daily trainer than a stripped-down race shoe.

Stack checks read 50.8 mm and around 51.4 to 51.6 mm on the two heels, placing it squarely in the above-50 mm club. The forefoot is aggressively squared off at the tip, retaining around 31 mm of stack under the big toe, versus something like 9 mm in a traditional trainer.

Build quality is mostly strong, which is worth highlighting given recent Adidas inconsistencies. The one flaw found was a small visible paint gap between the yellow foam puck and the plate on one shoe, hard to see at a glance but noticeable on close inspection. At $300, that is fair game to call out.

First Run Impressions

The first run was a hot, humid six-miler with several miles at or near marathon effort, and the shoe left a complicated impression. The verdict: it is a banger, and also a very weird shoe.

The heel is soft, squishy, and comfortable, similar to the Adidas Adios Pro 4 but a touch softer. The forefoot delivers a firm, bouncy pop that has been described as trampoline-like. The combination makes the Strung 3 feel like the best version of the Strung 2, executing what that shoe was trying to do. It encourages you to run hard.

At slow jogging paces, though, it does not work well. The reverse-pizza geometry, a heel narrower than the forefoot, makes it feel clownish and sloppy at easy efforts. This is a shoe that needs power. Think of it as a big, flashy, overbuilt performance machine: impressive when driven hard, cumbersome when cruising. Heel lockdown was imperfect too, with some heel slip during the run.

Who Should Buy It

If you want a new experience, something weird, bouncy, and genuinely different from anything else in the lineup, this shoe delivers. It shines as a Zone 3 cruiser or a long-run shoe for runners who want fun and maximum protection rather than pure speed. For bigger or more powerful runners, it could genuinely work as a marathon shoe, much as the Strung 2 did for many.

If your priority is a fast marathon shoe, look elsewhere. The OG Prime X Strung remains the superior all-rounder, and the brand’s faster race shoes, including the Adios Pro 4, are better suited to PR attempts. The Strung 3 is not the fastest option in the lineup, and it does not fully return to the OG’s disappearing-on-foot character.

It is not a perfect shoe. It has quirks: the clunky forefoot feel, the odd geometry at easy paces, the questionable value of the Strung upper, and a $300 price tag. But expensive flagship shoes are often about experience rather than perfection, and on that front this one succeeds. It is exciting, bouncy, protective, and built to last, with earlier versions in the family known to hold up well beyond 700 miles.

Conclusion

The Prime X Strung 3 is a thumbs up and a B-plus on first run. It is not a return to the OG, but it is a genuine improvement on the Strung 2 with a softer heel, a fun bouncy ride, and plenty of headline tech. Longer runs should suit it even better. If you want the most exciting, over-the-top shoe in Adidas’ lineup and you are happy paying for the experience, this is it. If you want the fastest marathon shoe, the OG or the brand’s conventional racers remain the better picks.